Abstract: A method of measuring at low frequency the electrical conductivity of a hrogeneous soil sample contained in an electrically insulating soil container or cell having at least two, or a colinear array of three or more, chemically inert probes or electrodes wherein the soil cell first is calibrated using a standard solution of known conductivity to obtain a cell constant k for each pair of probes. The cell constant for a given pair of probes is the product of the resistance measured between said pair of probes and the known conductivity of the solution. This cell constant is representative of the factor 1/a in a formula for resistance R = .rho. 1/a of a material where .rho. is the resistivity of the material between adjacent probes, 1 is the length of the material -- substantially equal to the probe spacing -- and a is the cross-sectional area of the material through which the current flows between the pair of probes under consideration.